Adding SMS to your authenticator-enabled account is a security downgrade.

tl;dr: Basically, title. Adding the SMS Protect feature to an account that already has a TOTP authenticator enabled is a security DOWNGRADE. My personal opinion is, don't do it just for 4 more bag slots inventory spots.context: Authenticator and SMS Protect are both required to get the 4 extra bag slots inventory spots; not just Authenticator.detail: One of the features of SMS Protect is that it allows you to "remove a lost authenticator" using an SMS text message. This means SMS Protect can be used to completely bypass your secure TOTP 2FA authenticator.But SMS out-of-band security channels are considered highly insecure at present; certainly far more so than the relatively strong TOTP 2FA authenticator it can bypass.If you have an account that has a TOTP authenticator enabled and add SMS Protect to it, you are DOWNGRADING your overall account security. Not worth it for 4 bag slots inventory spots.sources: This Verge article is pretty good. Or the NIST guidelines that state that any out-of-band auth sent over the PSTN (telephone network) is considered RESTRICTED, i.e. not to be used unless the security risks are well understood (§5.1.3.3).EDIT: Re-worded a thing because I was accidentally getting people excited about a ton of extra bag space, and I prefer to get people excited on purpose.